LATHROP – Voters in Lathrop overwhelmingly approved a one-cent sales tax increase back in November. And come next month they’re start paying it.It will take Lathrop’s sales tax from 8 percent to 9 percent - the highest in the Northern San Joaquin Valley. Sales tax rates for nearby cities are Manteca and Tracy 8.5 percent; Stockton, 8.25 percent, Lodi, Ripon, and Escalon 8 percent; and Modesto 7.625 percent.After months of waiting and jumping through all of the administrative hoops that come with expanding local taxes, local businesses will officially start collecting the one-percent on April 1 – the same day that Mayor Sonny Dhaliwal will appoint the city’s first oversight committee tasked with making sure the money is spent in accordance with what voters approved.